Inductance device



W. L. CA$PEW ET AL INDUCTANCE nmnmm Filed April 23;, 192% Patented Aug. 4, 1925.

UNITED STATES 1,548,022 PATENT OFFICE.

WILLIAM L. CASPEB, O1 BROOKLYN, NEW YORK, AND ERNEST L. SCHWARTZ, 01' EAST ORANGE, NEW JERSEY, ASSIGNORS '10 WESTERN ELEGIRIC COIRANY, INCORPO- RATED, NEW YQRK, N. Y., A CORPORATION OF NEW YORK. i

muc'mncn nmcn Application fledAprll 88, 1928. Serial No. 884,044.

To all whom it may concern:

Be it known that we, WILLIAM L. Casrnn and ERNEST L. SCHWARTZ citizens of the United States, residing at lSrooklyn, in the county of Kings, State of New York, and East Orange, in the county of Essex, State of New Jersey, respectively, have invented certain new and useful Improvements in Inductance Devices, of which the following is a full, clear, concise, and exact description.

This invention relates to inductance de-' vices and more particularly relates to transformers.

a shielding arrangement between two windings of an inductance device such as a transformer.

A second object of the invention is to rovide an arrangement whereby the various windings of an inductance device may be independently wound and assembled in an economical manner.

Shielding means between the primary and 95 secondary windings of a transformer in a signaling circuit are frequently of importance in reducing electrostatic effects between the windings. For example,'shielding. means between transformer windings 8 are particularly desirable when the transformer is used in a physical circuit which is also phantomed whereby the phan'tom currents in the primary winding may be prevented from passing over to the seconda winding due to capacity between the win ings which tends to give rise to cross-talk between the physical circuit and the phantom circuit.

In order to reduce the capacity efiects beeO tween the windings of an inductance device,

the shielding arrangement hereinafter described in detail employs a metallic spool on which the inner winding is wound. A metal sheet is slipped over this spool and arranged to form with the spool and its projectlng ends a substantially complete me tallic enclosure for the inner winding except for the necessary small'aperture or apertures through which the leads for the winding pass. The other windin is then wound on a spool which may be 0 insulat ing material having such dimensions as to fit snugly over the metallicsheet. With the spool and sheet grounded, the arrangement sents the manner of assem An object of this invention is to provide substantially eliminates not only direct ca,- pacityefiects between the two windings but also eliminates the indirect capacity eilects due to each windin having a capacity to the core or case emp oyed.

Referring to the drawin s, Fi 1 repre- 1y 0 the various parts of the transformer embod ing this J invention. Fig. 2 shows the assem 1y after 7 a the core material has been inserted within the windings, and Fi 3 illustrates an elecinvention is of particular application in reducing cross-talk diificulties.

. Referring to Fi 1, the primary winding 7 5 is shown woun on a metallic spool-6 having squared, ends 7. If desired, the winding 5 may be'wound in a plurality of sections, two, for example, a metallic separator 8 of similar size to the end pieces 7 of the spool being provided at the center to separate the two alves of the winding. A sheet of metal is then bent to form a cover 9 of such a size as to fit snugly over the spool '6, the cover resting on the end pieces 7 and the separator 8 and forming with the 90 s 001 a substantially complete metallic enc osure for the winding 5. In general, it would be undesirable for either the spool 6, the and pieces 7, separator 8, or the cover 9 to be circumferentially complete and an air ga is arranged at the point 10 alon the spoo The end pieces 7 are-similarly broken and disconnected at the same point and the two ends of the cover 9 are spaced apart a distance equal to the air gap in the spool. Care should be taken of course to lace the cover 9 on the spool such' that the air gap in the cover 9 occurs at the same point asthe air gap-in spool 6 and end pieces 7. It is, of course, obvious that the air aps in members 6, 7, 8 and 9 may be Y filled with insulating material or other material of high resistance since the precaution to be taken is merely to prevent the transformer from having a short circuited turn of low resistance. t The secondary winding 11 is preferably wound on'a second spool 12 which may be of insulating material and having such internal dimensions that it may be readily slipped over the cover 9*in order that the secondary winding-may be superposed on the primary winding in an eflicient manner.

05 trio circuit in which t e-transformer of this the transformer ma be put in place as shown in Fig. 2. he core, for example,

may comprise a plurality-of L shaped and- F shaped laminations which are fitted into the spool 6 in the usual manner to form a magnetic circuit.

In many cases, it will be found desirable to insure good contact between the cover 9 and the end pieces 7 by soldering them toi gether. or connecting them in any other suitable manner. The metallic box comprising the s 0016, end ieces 7 and the cover 9 may then grounded Such a metallic enclosure for the winding 5 has been found to substantially eliminate capacity effects between the primary and secondary windings of va transformer to a high degree. The metallic enclosure not onl eliminates the direct capacity between t e two windings but alsoeliminates the indirect capacity efi'ects due. to the capacity each winding may have to the core a or the housing containing the windings. In

one case a transformer made in this manner had a capacity between windings of less than one micro-micro-farad.

It is to be understood, of course, thatthe windings and the core structure shown in Fig. 2 may be treated and potted in any de-' sirable manner in order to provide a. satisfactory housing for the same.

The transformer described above has been found particularly useful to employ-as the input transformers 14 and 15 of a phantom group repeater of the type shown, for example, in Fig. 3. The phantom currents flowing, for example, in parallel over line conductors 15 and 16 due to capacity efiects between the primaryand the secondary windings of transformer 14 will tend to be impressed upon the side circuit vacuum tube repeater 1 thereby giving rise to cross-talk between the side circuit and the phantom circuit; the effect of this capacity is especially accentuated because the transformer usually is a high step-up transformer which causes a high voltage to be developed across the secondary winding. When, however, the primary winding of the input transformer 14 or similar input transformer 18 is onclosed in a metallic box of the t pe described above, it has been found t at this cross-talk difiiculty. is substantially eliminated. i

It is to be understood that the feature of winding the primary and secondary windings on separate spools which are later su rposed ma be em 10 ed in other cases th ii the one escri' a ove in which its particular use is to aid in the reduction of cross-talk. Other modifications of this invention will occur to those skilled in the art and it is to be understood that this inby suitable ground wire 13.

- around said core, a windl bodiments without departi in anywise from the spirit of this invention as defined vention may pbssess widely different em- 2. An inductance device comprising a core, a metallic spool having projecting end pieces around said core, an inductive winding wouInd on and supported b said spool, a metal ic cover for said s 00 said cover and said spool forming a su tantiall complete metallic closure for said win ing a second spool fitting over said cover, an a second winding wound on said second spool.

'3. An inductance device comprising a core, a metallic spool having projecting end pieces surrounding said core, said spool orming an incomplete turn around said core, a winding wound on said spool, a cover for said spool supported by the projecting ends of said spool, said cover forming an incomplete turn around said winding, and a second winding surrounding said cover.

4. A transformer comprising a core, a spool having projecting end pieces surrounding sa1d core having a rectangular opening, said spool being slotted to make said spool circumferentially incom lets, a winding wound on said spool, a sti meta-llic cover surrounding said winding and supported by the projecting end pieces of said spool, a second spool fitting over said cover, and a second winding wound on said second s 001.

5. inductance device comprising a core, a circumferentially incomplete metallic spool having projecting end pieces wound on said spool, and a circumferent1ally incomplete cover for said spool.

6. An inductance device comprising a core, a metallic spool having projectin end ieces around said core, the ends an the diy of said spool being slotted to make sai spool circumferentially incomplete, a winding on saidspool and a slotted cover for said spool supported by the ends of said spool and having the slot in the cover coin-- ciding with the slot in the spool.

7. A transformer comprising a hollow metall-ic support member serving as a spool, windings wound thereon, a core of metallic material within the sup ort member, a sec ond support member of magnetic material surrounding said hollow support member, and windings on said second support mem ber, said two support members serving to substantially completely enclose one of said windings to electrostatically shield said two substantially completely electrically .shield windings from each other. said two windings from each other. 10

8. A transformer comprising superim- In witness whereof we hereunto subscribe posed coils, one of said coils being wound our names this 12th and 17th day of April,

on a metallic supporting spool, another of, A. D., 1923.

said coils being wound on another metallic supporting spool, the second spool surround- WILLIAM L. CASPER.

ing the first and cooperating therewith to ERNEST L. SCHWARTZ. 

